The invention relates to an abdominal wall reinforcement for the treatment of inguinal hernias by an anterior route and without tension.
In the treatment of parietal insufficiencies (hernias and eventrations for the most part), the aim of reinforcement is to give a permanent mechanical support to the surgical reconstruction. The reinforcement is all the more effective, and its local tolerance all the better, if it integrates in the tissue intimately and at an early stage. To achieve intimate and early integration without formation of a peripheral fibrous shell, the macroporosities of the implant must be as widely open as possible to the outside and the elasticity of the reinforcement must allow it to follow the physiological deformations of the wall. The limits are fixed by the mechanical resistance of the textile, which must be greater than 10 decanewtons in the standardized ISO5081 test, by the maneuverability by the surgeon, and by the impossibility of hernia recurring through the pores of the tissue which must be a maximum of 7 to 10 millimeters in diameter.
The concept of a tissue reinforcement of the abdominal wall in the form of a knitted textile has been known for decades in the scientific literature. A number of technical solutions have been described, in particular in the following documents: U.S. Pat. No. 5,569,273, WO 96/03091, EP 0,797,962, FR 2,766,698. These all have in common the knitting of monofilaments or multifilaments of polypropylene or polyester.
In a known manner, such tissue reinforcements have to meet a number of requirements, and in particular they have to have a mechanical strength in all directions, be biocompatible, flexible and conformable, while having a certain elasticity, be porous and transparent, be able to be sutured and recut, while at the same time being non-tear and runproof, and, finally, they must be sterilizable and durable. In general, these reinforcements are knitted and made up of several sheets of interlaced yarns.
Specific forms of these textiles which are able to conform, on the one hand, to the anatomy of the inguinal region and, on the other hand, to the surgical technique employed have also been known for many years, both for posterior access routes (EP 0,836,838, WO 95/07666, WO 96/41588) and for anterior access routes (U.S. Pat. No. 5,356,432, EP 0,827,724). While in general the reinforcements designed for the posterior access routes are of large dimensions and require only a small number of fixing points, the reinforcements designed for the anterior access routes are of smaller dimensions, are slotted (in advance or extemporaneously) to surround the spermatic cord and therefore require relatively extensive fixing, on the one hand in order to close the slit on itself, and on the other hand to oppose the intra-abdominal forces of extrusion and, finally, to guarantee rapid integration with the peripheral tissues.
The present invention relates to a novel type of knitted reinforcement specially adapted to the treatment of inguinal hernias by an anterior access route and placed in a premuscular location, affording ease and speed of use, securing of its position by the practitioner, and effective functional repair for the patient.
This reinforcement consists of a reinforcement piece and of a flap connected to this reinforcement piece; the reinforcement piece is made of an openworked prosthetic knit consisting at least partially of multifilament yarns and has a slit for its engagement around the spermatic cord; this prosthetic knit can in particular be that described in French Patent No. 2,766,698; the flap is able to be folded over the slit.
According to the invention, the flap is shaped in the form of a sector of a circular annulus and is connected via one of its radial edges to one of the edges of the reinforcement piece which delimits the slit, the shape of the flap being such that the flap, when folded over said slit, is inscribed on the medial half of the reinforcement piece, without protruding beyond the edge thereof.
The connection of the flap to one of the edges of the reinforcement piece which delimits the slit makes it possible to perfectly secure the flap to the reinforcement piece and to perfectly maintain this same edge of the reinforcement piece after the reinforcement has been put into place.
The abovementioned shape of the flap, in the form of a sector of a circular annulus, allows the flap to have a large surface area in contact with the reinforcement piece, for a perfect connection of this flap to this piece; this shape at the same time ensures that the inner arched edge of the flap does not interfere with the spermatic cord and that the outer arched edge of this flap does not extend beyond the edge of the reinforcement piece, towards the outside thereof, and therefore does not interfere with the surrounding tissues.
This shape of the flap additionally favors folding of this flap against the reinforcement piece once the reinforcement is in position.
The radius of the circle in which the flap is inscribed can be from 80 to 100 mm, in particular 90 mm.
According to a preferred embodiment, the reinforcement has the general shape of an ellipse, comprising a lower edge with a large radius of curvature which is able to match the crural arch as far as the pubis, two ends with a small radius of curvature, and an upper edge with rectilinear parts and a curved part, while the slit, arranged in the upper part and substantially halfway along the length of the upper edge, perpendicular to its rectilinear edge, opens via its inner end into a circular orifice for lodging the spermatic cord and securing the reinforcement.
This reinforcement satisfies the traditional requirements of the wall reinforcements mentioned above and, by virtue of its particular shape, widely covers all the zones of potential weakness, while at the same time being easy to put into place.
The upper position of the slit facilitates the deployment of the lateral parts of the reinforcement under the aponeurosis of the greater oblique muscle. The circular orifice receiving the spermatic cord suppresses all shearing stresses on this cord and improves the positioning and securing of the reinforcement.
The flap, on its face which is to be folded over the reinforcement piece, preferably comprises means, integral therewith or attached to it, for fastening or joining to the knitted structure of the reinforcement piece, for example grip means.
In one embodiment, the flap is made of a prosthetic knit satisfying the requirements set out above and comprising, projecting from its face which is to be folded over the reinforcement piece, spiked naps formed by a monofilament yarn and having a length allowing them to penetrate into and attach themselves in the knitted structure of the reinforcement piece without protruding from the latter.
Depending on the applications, this monofilament yarn is made of biocompatible polymer or of bioabsorbable material.
Once the flap has been folded over the reinforcement, the spiked naps engage in and between the multifilament yarns of the knit of the reinforcement, which ensures that the flap is locked in position. This locking, effective even in a liquid environment, is sufficient to secure the closure of the slit and offer mechanical resistance to the tangential stresses, while permitting the flap to be unfastened by traction in order to adjust its position.
The density of the spiked naps is determined as a function of the prosthetic knits used but is between 50 and 90 naps per cm2.
Likewise, the length of the naps, measured from the base projecting from the attachment sheet to the top of the spike, depends on the thickness of the prosthetic knit forming the reinforcement piece, but is between 1 and 2 millimeters.
The reinforcement piece itself can comprise means, integral therewith or attached to it, for fastening or joining, for example grip means, projecting from one and/or the other of its main faces, these fastening or joining means being able to permit the fastening or joining of this reinforcement piece to the tissues in contact with which this reinforcement piece is intended to be placed.
These fastening or joining means can have a structure identical to that, described above, of the means for fastening or joining the flap to the reinforcement piece.
The knit from which the reinforcement piece is made can be of the xe2x80x9cflat knitxe2x80x9d type or can have two porous layers connected by connecting yarns, the weave forming runproof transverse channels opening out from the two porous layers.